This invention relates to a plate for radiant heating made from natural or cast stone with a channel disposed within the plate body or upon the plate surface for acceptance of a heat carrier or electrical heating conductor, where both ends of the heat carrier or the heating conductor issue extend outside the plate.
Federal Republic of Germany Patent Application DE-OS No. 2 336 902 discloses a plate made from clay-like materials which provides radiant heating. This plate contains an extended tube-like cavity which is embedded into the plate while it is castable and malleable. This procedure is suitable neither for natural stone nor for plates consisting of concrete, which are desirable mainly because of their higher strength, but also because of their many other properties useful for radiant heating. It is extremely difficult to provide in a natural stone plate boreholes parallel to the surface thereof for containing a heat carrier or an electrical heating conductor. Therefore a practical way of providing natural stone plates or concrete plates with such channels for accepting a heat carrier or a heating conductor.
This objective is achieved according to the present invention by furnishing a plate of natural stone or concrete with a groove which is sunk into the outer surface of the plate, the groove being closed flush with the surface of the plate while leaving a cavity in the groove. Such grooves may be cut into the plates or milled into the plates by appropriate cutting tools.
It was found to be particularly advantageous to dispose in the groove a tube or a pipe and to fill the remaining groove space with a filler. Such filling may be done with a synthetic resin, especially an epoxide resin containing a filler such as rock meal. This procedure does not impair the appearance of the plate. On the other hand it is comparatively easy to manufacture such channels using natural stone plates.
When one wants to expend the labor for sinking the grooves and particularly when one wants to increase the length of heat carrier or heating conductor per unit of plate surface area, the invention provides that the grooves are circular, where two adjacent grooves overlap each other by one groove width and such that the heat carrier or the electrical heating conductor bends in an opposite direction as it passes from one circular groove to the adjacent groove.
According to experience, a tool rotating about an axis perpendicular to the plate surface, such as an annular cutting die head, is more effective than a conventional knifing disk for forming the grooves. The work-piece may be fastened for this method of groove formation. The toolhead, containing in some instances several tools, may be changed in a predetermined path of motion after cutting each individual circular groove. The overlap of the circular grooves allows easy transit of a pipe or a conductor within two circular grooves, in which case the direction of transit changes. The pipe or heating conductor thereby assumes a snake-like shape so that a large amount of heat carrier or heating conductor may be disposed per unit area of the plate. The circular grooves allow the pipe or conductor to be guided in circular arcs without sharp bends so that trouble-free passage of heat producing current is guaranteed.
In the simplest embodiment, it is sufficient to provide a continuous row or rows of circular grooves on the plate surface. In another embodiment the circular grooves are arranged at regular intervals in rows running perpendicularly to each other. In such embodiment, the heat carrier pipe or the heating conductor is guided with a looping angle of 180.degree. when making the transit from one circular groove to the next groove within the same row and with a looping angle of 270.degree. at the turning point at the end of each row when making the transit from one groove to the next groove within an adjacent row. Each parallel row of circular grooves is occupied by a single length of heat carrier pipe or heating conductor, in which case the pipe or conductor ends are provided with appropriate fitting elements.
In an alternative embodiment, the circular grooves are arranged at regular distances in rows running at acute angles to each other. In this embodiment, the snake-like shape of the pipe or conductor is less widely undulating, which may be advantageous under certain circumstances.
In order to obtain a continuous groove for accepting the pipe or the conductor, it may be advantageous to open the outermost portion of the circular grooves of the outermost rows at one or more plate edges. It is within the scope of this invention to close these outlets on the edges of the plate. Such closing may be done also with a synthetic resin or a stone-like material.
According to another feature of the invention, the outer diameter of the pipe or hose disposed in the groove corresponds to the inner width of the groove. This feature causes maximum utilization of the cross section of the groove as well as a high cross section of streaming. The same can be said for the electrical heating conductor, which is usually formed as a coil or a helix. The pipe or hose is preferably fitted with ribs.
It is also within the scope of the present invention to close the groove worked into the plate surface with an additional, adjoining plate. In this embodiment the heat conducting mass is considerably enlarged by such provision of a second stone plate. Thereby the closure of the groove may be performed in a particularly easy manner. In this case, of course, pipe or hose may be placed within the groove. Both plates may be glued together by using a suitable synthetic resin. The second plate may consist of a plate formed of metal or synthetic material or also multiple layers of materials.
Another embodiment of the invention provides that the groove consists of a substantially planar container whose outline corresponds to the outline of the plate surface. The outline of this container is a little smaller than the outline of the plate surface, and the container lies sandwiched between the two plates, with each of its sides in facing engagement with each plate. The two plates are connected to each other and spaced at a distance corresponding to the thickness of the container. The remaining interstice between the plates is filled with a suitable filling material. The formation of the grooves in the plate face is here obviated. Both plates are easily maintained at the desired distance by spacers so that the container walls abut the plates. The interstice, existing in the region of the outer edges of the plates, is preferably filled with a synthetic resin, particularly an epoxide resin so that a closed cladding panel results, which may be prepared as a unit and may also be mounted as a unit.
In another alternative embodiment, one plate or both plates are provided on their mutually opposing faces with an indentation for accepting the container, the maximum depth of the total indentation corresponding to the thickness of the container, and the shape of the indentation corresponding to the shape of the container. In this case too the surfaces of both plates abut, with exception of the surface area comprising the indentations in one or both plates. In the situation where the depth of the indentation is less than the thickness of the container, a spacer is provided to maintain the plates at a suitable spacing and a filler is used to fill the remaining gap. Otherwise, the two plates abut in the region near their edges.
The container according to another embodiment of the invention is formed of rubber or another material of similar properties, such as a synthetic resin. It may also be formed of sheet metal and, in that case, may have components which are interconnected and which are able to define individual channels.
In the embodiments where the two plates abut in the region near their edges, the channels or grooves open at the plate edges. The channels may communicate with the channels in another similar plate arrangement by suitable pipe connections so that the channels of a plurality of such plate arrangements are connected in series. It is also possible to have the channels open into the surface of a plate. Such construction is particularly suitable when a connection to pipes from a heating unit is desired.
Such plate arrangements may be extensively used for the cladding of brick or cement buildings and may be fastened thereto by wall anchors. The sometimes very large facades of buildings are often exposed to considerable irradiation by sunlight, which hitherto has not been utilized. Conventional solar collectors are usually located on rooftops where they are out of the way. Nevertheless the integration of solar collectors in the architectural design of a building is an extraordinarily difficult problem, especially when the collector is located at the outside of a building wall and is immediately connected to a heat reservoir within the wall or is connected through such reservoir to a heater located at the inside of the wall. Moreover, such collectors are now provided with a transparent outer cover and are unesthetic. The degree of effectiveness of such a solar collector arrangement, even with an immediate spatial connection of collector, heat reservoir and heater, is low and is suitable only at high irradiation levels.
Effective use of extremely large facades of buildings has not been accomplished. Therefore an urgent need exists to solve this problem in a manner suitable for architectural preferences. The above described plate arrangements of the present invention may easily be included in a solar heating system furnished with a conventional heatpump and leave the general esthetic appearance unimpaired, while effectively using heat resulting from incident sunlight.
Other features which are considered characteristic of the invention are set forth in the appended claims.
Although the invention is illustrated and described in relationship to specific embodiments, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.